How to Find Public AWS Lambda Functions

Publicly accessible services could expose sensitive data to bad actors.

info

This security check is part of the CIS Amazon Web Services Benchmarks and is rated severity high.

Prerequisites

This guide assumes that you have already installed and configured Fix Inventory to collect your AWS resources.

Directions

1. Execute the following search command in Fix Inventory Shell:

   > search is(aws_lambda_function) and function_url_config.auth_type not in [null, AWS_IAM]
   ​kind=aws_lambda_function, ..., region=fixinventory-poweruser
   ​kind=aws_lambda_function, ..., account=poweruser-team

2. Pipe the search command into the dump command:

   > search is(aws_lambda_function) and function_url_config.auth_type not in [null, AWS_IAM] | dump
   ​reported:
   ​  id: /aws/lambda/123
   ​  name: some-name
   ​  ctime: '2022-12-05T22:53:14Z'
   ​  kind: aws_lambda_function
   ​  age: 2mo28d

   The command output will list the details of all non-compliant aws_lambda_function resources.

Remediation

• Define an authorizer for your Lambda Function.

note

Please refer to the AWS Lambda documentation for details.

Further Reading

• Search
• Command-Line Interface
• aws_lambda_function Resource Data Model

External Links

• CIS Amazon Web Services Benchmarks
• AWS Documentation